By Edward Tetz

Part of Cisco Networking All-in-One For Dummies Cheat Sheet

While you may not use the OSI model every day, you should be familiar with it, specifically when working with Cisco switches and routers (which operate at Layer 2 and Layer 3, respectively). Here are some of the items that operate at each level of the OSI model:

Layer Description Examples
7. Application Responsible for initiating or services the request. SMTP, DNS, HTTP, and Telnet
6. Presentation Formats the information so that it is understood by the
receiving system.
Compression and encryption depending on the implementation
5. Session Responsible for establishing, managing, and terminating the
4. Transport Breaks information into segments and is responsible for
connection and connectionless communication.
3. Network Responsible for logical addressing and routing IP, ICMP, ARP, RIP, IGRP, and routers
2. Data Link Responsible for physical addressing, error correction, and
preparing the information for the media
MAC address, CSMA/CD, switches, and bridges
1. Physical Deals with the electrical signal. Cables, connectors, hubs, and repeaters